The invention concerns a device for operating a valve drive of an internal combustion engine comprising a switching mechanism for switching to different valve lift curves of a gas exchange valve. The invention further concerns a method of operating a valve drive of an internal combustion engine.
Such switching mechanisms effect a reduction of friction in the valve drive especially at low to medium rotation speeds of the internal combustion engine by actuating only one of preferably two gas exchange valves in opening direction. However, since the switched-off element executes an idle stroke against the force of a spring, unnecessary friction still occurs on this element. In addition, the element in question is retained by the force of this spring on the control cam concerned. If, now, a switching-off is required at high rotation speeds, the spring used must be very strong but the limited design space restricts this possibility so that the maximum rotation speed of the internal combustion engine has also to be limited. Moreover, if the moment of time of re-switching is unfavorable, increasing noise and wear problems can occur.